Every endeavor has been made for higher sensitization and reduction of residual colors after processing of a silver halide photographic material. It is known that a sensitizing dye which is used for spectral sensitization exerts a great influence on the capabilities of a silver halide photographic material. A trace of structural difference of a sensitizing dye largely affects photographic capabilities such as sensitivity, fog, storage stability and residual colors after processing. Photographic performances are also largely influenced by the combined use of two or more kinds of sensitizing dyes but it is difficult to foresee its effect. Many engineers have hitherto synthesized various kinds of sensitizing dyes, examined the combined use of sensitizing dyes and endeavored to investigate photographic capabilities thereof, however, it is not possible to know photographic capabilities in advance yet.
For that reason, a technique of spectral sensitization capable of improving sensitivity of silver halide grains without causing adverse effects such as fog and residual colors has been required.
Also, it is known that the present durability is deteriorated by adsorbing onto the surface of silver halide grains the sensitizing dye used for the spectral sensitization. Accordingly, a sensitizing dye in which the pressure durability is not deteriorated is desired.